133results about How to "Suppress overvoltage" patented technology

The invention discloses a method for MMC type VSC-HVDC system precharge control. The method is based on a CPSM (carrier phase shifted modulation) strategy and controls by adoting a voltage outer ring and a current inner ring, wherein the voltage ring controls capacitor voltage of a sub-module, and the current ring controls three-phase AC current. The method disclosed by the invention gives consideration to the precharge speed and the precharge efficiency while limiting impact current and preventing overvoltage. The control method is clear in thinking, easy in engineering realization, and has good dynamic performance and steady-state performance.

The invention, which belongs to the optimization operation field of the power system, discloses a linear approximation solution method of voltage and reactive power optimization of a distribution network. An active distribution network reactive power optimization module is established by using reactive power outputs of a distributed power supply and a discrete reactive power regulating device in a distribution network as state variables and using the operation transmission loss of the distribution network as an objective function; linearization is carried out on an active distribution network reactive power optimization module to obtain a linear approximation model; and alternate iteration is carried out on a loaf flow analysis and the linear approximation model to solve a solution approximating an original non-convex problem. According to the invention, for the distribution network design with loop network operation, the reactive power regulation capability of the distributed power supply can be fully utilized to realize coordinated cooperation with other reactive-load compensation devices; over-voltage and under-voltage problems caused by grid connection of a distributed power supply can be solved; the operation losses of the distribution network can be reduced; the capability of the distribution network for absorbing the distributed power supply can be improved; the safe and economic operation of the distribution network can be guaranteed; and the model solution becomes simple and reliable and no non-feasible solution is generated.

The invention discloses a method for inhibiting an overvoltage and an overcurrent of a resonant transformation circuit and the resonant transformation circuit. The resonant transformation circuit comprises an inverter bridge, a transformer, a resonant capacitor, a resonant inductor and a resonant branch circuit connected in parallel with the resonant capacitor. The resonant capacitor, the resonant inductor and a transformer primary winding are connected in series. A series circuit of the resonant capacitor, the resonant inductor and the transformer primary winding is connected with an output end of the inverter bridge. The resonant branch circuit comprises an auxiliary resonant capacitor and a pressure-sensitive device. The auxiliary resonant capacitor is connected in series with the pressure-sensitive device. By dynamically changing parameters of the resonant circuit, a voltage stress and a current stress of the resonant circuit under the abnormal working condition can be effectively reduced and the working reliability of the circuit is improved.

There is provided a power supply apparatus that is capable of suppressing the occurrence of anomalous electric discharge due to charge-up of a substrate and that is capable of forming a good thin film on a large-area substrate. The power supply apparatus of this invention has: a first discharge circuit that alternately charges predetermined potential at a predetermined frequency to a pair of targets that are in contact with a plasma; and a second discharge circuit that charges predetermined potential between the grounding and the electrode, out of the pair of electrodes, that is not charged with potential from the first discharge circuit. The second discharge circuit is provided with a reverse potential charging means for charging, at the time of polarity reversal, at least one of the electrodes with potential that is reverse to the output potential.

The invention discloses a low-voltage ride through control method and a low-voltage ride through control device for a doubly-fed wind power generating system. The device comprises a reversible power converter, a motor controller, a signal detection circuit and a crowbar protection circuit. The crowbar protection circuit consists of a three-phase uncontrolled bridge rectifier, a primary release circuit and a secondary release circuit. When a power grid has a low-voltage failure, the reversible power converter stops working, the primary and secondary release circuits in the crowbar protection circuit are switched on at the same time and work in parallel to rapidly release transient impact current in a rotor winding of a doubly-fed motor; when the current of a rotor attenuated to a rated value, the secondary release circuit stops working, and the primary release circuit is still switched on to release the transient current in the rotor wining; and after the low-voltage failure of the power grid is eliminated to recover the voltage of the power grid, the reversible power converter restarts working, and the crowbar protection circuit completely stops working. By the method and the device, high ride through capability and good effects are ensured, the time of a transient process for low-voltage ride through can be shortened, the voltage recovery of the power grid can be accelerated and secondary over-current can be effectively prevented.

An inverter circuit provided in a power conversion device includes a full-bridge inverter, and a short circuit part. The short circuit part includes switching elements and clamp elements connected to the switching elements. The clamp elements suppress application of an excessive voltage such as a surge voltage to the switching elements.

The invention discloses a removing method and a control apparatus for alternating current filters for high-voltage direct-current power transmission. A constant value of the total number of the alternating current filters which need to be removed is set according to requirements of alternating current voltage and reactive power; the input alternating current filters are divided into two conditions, including the alternating current filters which participate in the filtering function and the alternating current filters which do not participate in the filtering function; the number of groups of the various kinds of equivalent removing filters of the alternating current filters which participate in the filtering function is determined according to the minimum filter configuration table; if the number of the groups of the alternating current filters which do not participate in the filtering function is greater than or equal to the constant value of the total number of the alternating current filters which need to be removed, only the alternating current filters which do not participate in the filtering function are removed; or otherwise, the alternating current filters which do not participate in the filtering function, and the alternating current filters which participate in the filtering function in the residual groups are removed; when the alternating current filters which participate in the filtering function are removed, the number of the removing groups of each type is calculated according to the filtering performance; the alternating current filters are removed in sequence rapidly; and therefore, the overvoltage of the alternating current power grid can be effectively restrained, or the reactive power requirement can be rapidly satisfied.

A power conversion device includes a high-pass filter for extracting an AC component of voltage Vdc of a DC link section, a multiplier for multiplying output VdcAC of the high-pass filter by a first gain K1 and outputting the result, a multiplier for multiplying output of the multiplier by a second gain K2 and outputting the result as a d-axis voltage correction signal vdcmp*, and a multiplier for multiplying output of the multiplier by a third gain K3 and outputting the result as a q-axis voltage correction signal vqcmp*. The gate signal generation section generates gate signals on the basis of a signal vd1 obtained by adding the d-axis voltage correction signal vdcmp* to a d-axis voltage command value vd* and a signal vq1 obtained by adding the q-axis voltage correction signal vqcmp* to a q-axis voltage command value vq*.

The invention relates to a high-reliability thermal-protection piezoresistor. An overheating separation node is arranged at each of two surfaces of a resistor disc, and the positions of the nodes are selected properly, so that the current separation range of the piezoresistor is wide from several mA to 100A, the separation speed is high and is faster than that of most of existing products under large current by 10 times, the safety is good, and the firing is avoided; the piezoresistor can be used independently and also can be used as a chip of a surge protection device (SPD) for preventing lightning overvoltage, operation overvoltage and other surge overvoltage, so that the electrical and electric devices and equipment are protected; when the piezoresistor is used in a use circuit, a fuse protector or an air switch for preventing the short circuit of an upstream piezoresistor can be omitted.

The invention discloses neutral-point grounding control equipment of a medium-voltage power grid. The neutral-point grounding control equipment comprises a bus voltage transformer, a grounding transformer, a circuit zero-sequence current transformer and a controller, wherein the bus voltage transformer is connected with a bus and the controller, the grounding transformer is connected with the busand an arc extinguishing coil, a neutral point current transformer and a neutral point voltage transformer are arranged between the grounding transformer and the arc extinguishing coil and are connected with the controller, a branch is arranged between the neutral voltage transformer and the arc extinguishing coil and is connected with a resistor by a switch connected with the controller, the controller is connected with at least two branch lines by the circuit zero-sequence current transformer, and the branch lies are connected with the bus. The advantages of two grounding modes of neutral-point resonant grounding and resistance grounding are combined, the advantage that a line can be accurately selected by resistance grounding is maintained, residual current of a grounding point also canbe reduced, an arc light grounding overvoltage is limited, an appropriate working mode can be selected according to different conditions of a short-term grounding fault or a permanent grounding fault, the safety running of the line is guaranteed, and the power supply reliability is also improved.

The invention discloses a reactive power compensation device, and relates to the field of reactive power compensation. The reactive power compensation device comprises a controller, a synchronizing signal detection circuit, a thyristor, a non-power consumption switch, a capacitor, a magnetic latching relay, a close shutoff detection circuit and a reactor; the controller is connected with the synchronizing signal detection circuit, the thyristor, the non-power consumption switch, the magnetic latching relay and the close shutoff detection circuit; the thyristor is in a parallel connection withthe non-power consumption switch; the thyristor is connected with the capacitor through the reactor; the magnetic latching relay is connected with the thyristor; and according to the synchronizing signal detected by the synchronizing signal detection circuit and the close or shutoff time of the magnetic latching relay detected by the lose shutoff detection circuit, the controller acquires a comparative result and rectifies the drive time of the magnetic latching relay according to the comparative result. The reactive power compensation device provided by the invention can effectively restrainthe high frequency flow and the overvoltage; when the device runs for a long time, the capacitor can be connected at the passing zero time of the voltage or disconnected at the passing zero time of the current; and thus, the service life of the magnetic latching relay and the capacitor is prolonged.

An overvoltage suppression device which suppresses overvoltage that occurs when breakers which turn on/off the connection between a power source bus and a power transmission line, are turned on after the breakers are turned off. The overvoltage suppression device measures the waveform of voltage on the side of the power source and the voltage on the side of the power transmission line, and extracts the waveform of a component in a predetermined frequency band on the basis of the waveform obtained by multiplying the wave shape of the voltage on the side of the power source by the waveform of the voltage on the side of the power transmission line. The breakers are turned on on the basis of a cycle wherein the waveform is peaked.

A controllable reactor with outside electrical source has main body and is made up by oil box, magnetic core pole inside of it, left and right side magnet yokes, up and down magnet yokes, winding of magnetic core pole and all kinds of sensor for detecting all species of parameters. It relates to rectifying and filtering equipment, detecting equipment for detecting electrical network parameter and control unit. The net-side winding, compensate winding and control winding set on the magnetic core pole from outside to inside. Net-side winding connects with transmit electricity circuitry, rectifying and filtering equipment connects with outside alternating current source, one end of control winding connects with input end of rectifying and filtering equipment, its output end connects with the other end of control winding to make up of feedback loops. The control unit joints with end boxes to main body connecting with all kinds of sensor signal, rectifying and filtering equipment and detecting equipment. Detecting equipment connects with transmit electricity circuitry and changes reactance value and capability of reactor by changing saturation and magnetic ratio of iron core.

Provided are a driving circuit for dynamic variable IGBT switching characteristics and a protection method thereof. The driving circuit for dynamic variable IGBT switching characteristics includes a pulse distribution and digital control chip, switch arrays and gate driving resistance arrays; the pulse distribution and digital control chip is connected with the input end of an IGBT upper bridge arm through a part of the switch arrays and a part of the gate driving resistance arrays, and connected with the input end of an IGBT lower bridge arm through the rest switch arrays and the rest gate driving resistance arrays; the pulse distribution and digital control chip receives the control pulse signals of a controller, receives status information fed back by the IGBT upper bridge arm and the IGBT lower bridge arm, outputs control pulse to drive the IGBT upper bridge arm and the IGBT lower bridge arm after completing pulse distribution, pulse self-locking, pulse interlocking and other treatments according to the control pulse signals and the status information, and meanwhile controls the switch arrays to dynamically change gate driving resistances. The switching characteristics are optimized, the switching loss is reduced, and besides, malfunction coding can be fed back to the controller so as to facilitate intelligent malfunction diagnosis.

The present invention provides a tripping logic simulating method for alternating-current filters of a direct-current converting station. A simulated loop model automatically cuts off a group of alternating-current filters according the voltage and the lasting time of an alternating-current bus of the current converting station; the alternating-current voltage of the alternating-current bus in the loop is adopted as an input parameter; the constant values of different over-voltage protection sections are compared through a plurality of comparative loop modules; an 'OR' gate outputs '1' or '0' level signals; after '1' signals are output when any constant-value condition of the protection section is met, a certain of delay requirements of relevant action are met, and one small group of alternating-current filters can be cut off, so that the over voltage of the alternating-current bus can be reduced; a plurality of small groups of alternating-current filters are continuously and successively cut off till the alternating-current voltage of the current converting station is lowered to a required value, so that the over voltage of the alternating-current bus is inhibited, and the safe running of a direct-current system is guaranteed.

The invention provides a peak closing method for a reactive compensation capacitor bank and belongs to the field of power quality of electrical power systems. According to the peak closing method for the reactive compensation capacitor bank, the optimum closing phase positions of all phases of capacitor banks are designed according to the fact that the capacitor banks are connected in parallel in the mode that the star-shaped neutral points are grounded or not grounded, the minimum delay time required from the moment a closing signal is received to the moment the on-off action is triggered is calculated according to the intrinsic closing time of a switch and external factors, and thus the capacitor bank is applied to a power grid when both the value of the voltage of the capacitor bank and the value of the voltage of a power grid are peak values. Compared with other closing methods, the peak closing method for the reactive compensation capacitor bank has the advantages that the voltage change ratio is lowered under the same closing time deviation condition, rush current and overvoltage which are generated during closing of the capacitor bank are reduced, power quality is improved, and the peak closing method has an extremely good application prospect on the occasion that reactive compensation is conducted by means of the capacitor bank.

A protection connection structure for preventing components in a variable frequency power cabinet from a flashover impact of a tested object is characterized in that a high-voltage resonance circuit common end G1 (including an exciting transformer high voltage tail and a load capacitor ground terminal), a resonance loop secondary common end and protective common end G2 (including a variable frequency power cabinet housing, an exciting transformer housing, a vehicle body ground terminal and a voltage divider ground terminal), and a control loop common end G3 which are in a loop in the variable frequency power cabinet are connected to the ground independently, a resistance-capacitance absorption device and a lightning arrester are additionally mounted between phases of a variable frequency power supply in the variable frequency power cabinet and between a phase and the ground respectively and are used for absorbing and inhibiting overvoltage, and a lightning arrester is additionally mounted on a high-voltage winding of the exciting transformer, so as to prevent an instant overvoltage generated by breakdown of the tested object from being coupled to a low voltage side.

The invention relates to a method for suppressing overvoltage between current converter bridges and a system thereof. A widely applied 12-pulse series-structured current converter structure is arranged in an ultrahigh voltage direct current project. In the unlocking process of the actual project, the trigger angle of a 12-pulse valve group probably has deviation, 24 times of harmonic wave is excited, and resonance is caused in a current converter loop by the 24 times of harmonic wave and relatively high overvoltage is generated between the current converter bridges. The size of overvoltage between the current converter bridges is detected firstly and compared with the set threshold value. If the size of overvoltage is greater than the set threshold value, a direct current filter is enabled to be disconnected before unlocking of the current converters next time, the loop of the 24 harmonic wave in the current converters is cut off and generation of overvoltage between the current converter bridges is suppressed. The method is effective, simple and convenient, normal unlocking is performed by overvoltage is suppressed and degree of complexity of a direct current power transmission system is not increased.

The invention discloses a method for coordination control of controllable shunt reactors. The method comprises the steps that a controllable shunt reactor control system submits the controllable shunt reactor lifting capacity to a master safety control station device through a home-station safety control substation device; when the master safety control station detects that line tripping occurs on a power transmission channel and the channel tide is larger than a certain value before the accident, the master safety control station sends information to the controllable shunt reactor control system through each safety control substation and locks the original control logic; the safety control substations collect the busbar voltage of each station after the accident and submit the voltages to the master safety control station, the master safety control station makes a decision in a centralized mode, and a command is given to put into part of capacity into the controllable shunt reactors according to the timing sequence if overvoltage is detected; the controllable shunt reactor control system receives and executes the command of adjusting the capacity; the original control logic of the controllable shunt reactor control system is open after a period of time. By the adoption of the method, coordination control of multiple sets of dynamic reactive power compensation equipment distributed in multiple transformer substations can be realized, overvoltage can be effectively restrained after the accident, and system voltage collapse caused by simultaneous incoordinate actions of multiple sets of controllable shunt reactors can be avoided.